I have three 2 week old chicks and one was quite a bit smaller than the others to begin with. I bought them at my local feed store at 5 days old. She seemed to have problems pooping, but I kept her bottom clean. She had been eating, drinking, acting like a normal chick, but yesterday I noticed she was quite lethargic and had runny white diarrhea. I separated her. I cleaned her a couple times yesterday and made her take sips of water. Today she died. I have cleaned the area and feeder and waterer where the other chicks are. This is my second time raising baby chicks. My other girls are almost a year old. I've never had any problems. How can I know if this was something contagious. If my other babies make it to be big enough to be introduced to my flock of 4, how will I know if they are carriers of something. For now, we are being very careful keeping them in isolation, hand washing, changing clothes, etc. I did notice today that the tiny sick baby had a large hard lump on her left neck. The other chicks seem to be fine for now. Please help. I'll be devastated if I do something to accidentally hurt my other chickens. I love these girls.